There are wide variations in physical configuration and cathead equipment among the available drill rigs used to perform the Standard Penetration Test (SPT). Such differences may be partly responsible for variations in blow count among different drill rigs. The paper draws attention to the fact that about one-half of the available drill rigs use clockwise rotation of the cathead while the remainder use counterclockwise rotation. Depending upon which direction is used, differences in the actual number of turns could be off by as much as 1/2 a turn. This difference could result in a substantial variation in the energy delivered to the sampler and in the blow count for the same soil conditions.

  • Supplemental Notes:
    • Pub. in Geotech. Test. J. Tech. Note 3, n3 p127-130 Sep 81.
  • Corporate Authors:

    National Bureau of Standards

    Gaithersburg, MD  United States 
  • Authors:
    • Kovacs, W D
  • Publication Date: 1981-9

Media Info

  • Pagination: 4 p.

Subject/Index Terms

Filing Info

  • Accession Number: 00344660
  • Record Type: Publication
  • Source Agency: National Technical Information Service
  • Report/Paper Numbers: Final Rpt.
  • Files: TRIS
  • Created Date: Dec 22 1982 12:00AM